By David Shepardson
WASHINGTON, May 26 (Reuters) - The U.S. National Transportation Safety Board on Tuesday called on the Federal Aviation Administration to revise how it assesses runway conditions during heavy rainfall, citing safety risks of airplanes skidding off the runway.
The recommendations follow NTSB investigations of 11 runway overrun accidents and incidents from 2008 through 2022 that occurred after landings on wet runways. The NTSB called on the FAA to reform the so-called Runway Condition
Assessment Matrix that uses a six-point scale for pilots.
The board cited the 2019 runway overrun of a Boeing 737 in Jacksonville, Florida, due in part to "an extreme loss of braking friction due to heavy rain and the water depth on the ungrooved runway, which resulted in viscous hydroplaning."
In the 2019 incident, a Boeing jet chartered by the U.S. military was arriving from Naval Station Guantanamo Bay in Cuba with 142 people on board when it slid into the St. Johns River at the end of the 9,000-ft (2,743-m) runway at Naval Air Station Jacksonville. There were no serious injuries.
The NTSB also recommended the FAA issue new rainfall intensity descriptors for aviation weather reports to identify rainfall intensities exceeding the current heavy rain threshold of 0.3 inch (7.62 mm) per hour.
The FAA said it takes NTSB recommendations seriously and will carefully consider those issued on Tuesday. The FAA encourages airports to report wet runway conditions.
The NTSB said wheel braking friction calculations for wet runways can be substantially less than those specified by FAA runway condition assessments due to limitations in the factors considered.
The NTSB said landing distances on wet runways calculated using the FAA model "can underpredict the actual landing distances required, thereby increasing the risk of a runway overrun."
(Reporting by David Shepardson; Editing by Jamie Freed)
